DE19915276A1 - Production of a magnesium alloy used e.g. in the manufacture of gear housing comprises extruding the alloy with a specified deforming degree - Google Patents

Abstract

Production of a magnesium alloy of high ductility comprises extruding the alloy with a deforming degree of at least 1.5. The alloy contains traces of less than 1.8 wt.% Cd, up to 0.1 wt.% Cu, up to 0.005 wt.% Ni and 0.5-20 wt.% Li, and at least 0.1 wt.% of further chemical elements. After extruding, the alloy has a breaking elongation of at least 20%, a compression strength of at least 300 MPa and an energy absorbed in fracturing of at least 70 J.

Description

The invention relates to a method for producing a high magnesium alloy Ductility u. a. through extrusion and the use of extruded semi-finished products or components.

Because of their very low density, magnesium alloys are approximately in the range of 1.2 to 1.9 g / cm ³ , occasionally, especially in the case of particularly lithium-rich magnesium alloys, down to about 0.9 g / cm ³ as metallic construction materials of particular interest for vehicle and aircraft construction. In the future, they will be used more and more for the lightweight construction of motor vehicles and airplanes in order to be able to compensate for the weight of additional elements due to increasing comfort and safety standards, particularly in new low-emission automobiles. They are also of interest for transportable devices or systems that are particularly light-weight for other reasons. The lightweight construction enables the construction of energy-saving vehicles and planes such as. B. the 3-liter motor vehicle. Among the manufacturing processes, die casting and reshaping, extrusion, forging, rolling and possibly subsequent reshaping such as stretching or deep drawing will become increasingly important in the future, since lightweight components such as B. seat, window and door frames, elements of vehicle cells and outer skins, housings, floor elements, covers, tank elements, tank flaps, brackets, supports, brackets, angles, crash elements, impact absorbers, impact shields and impact carriers, small parts or corresponding components for aircraft, for which there is an increasing demand.

The cold formability of the commercially available magnesium alloys is due to the hexagonal crystal structure and the associated low ductility limited. Polycrystalline magnesium and most magnesium alloys behave becomes brittle at room temperature. For a number of applications or for certain Manufacturing process of semi-finished products from magnesium alloys is in addition to good ones mechanical properties such as high tensile strength require ductile behavior. On improved forming, energy absorption and deformation behavior requires a higher one  Ductility and possibly higher strength and toughness. For this are To develop magnesium alloys with these properties or their To further develop manufacturing processes because many material variants match the manufacturing condition have widely varying material properties.

Ductility is the ability of a material to undergo a permanent change in shape, which in the uniaxial state is ideally without any elastic component according to the stress-strain diagram. This property is limited by the occurrence of the break. In general, the permanent elongation achieved in the tensile test up to fracture is considered ductility. As a measure of the ductility, the constriction of the fracture, impact work and notch impact work can also be viewed, each with a slightly different statement. These properties can be determined in accordance with EN 10 002, Part 1, or in accordance with DIN 50115 and 50116. The elongation at break A = A _plast characterizes the change in shape with its plastic part under a largely uniaxial load; in addition, according to the stress-strain diagram, the elastic part of the strain A _elast and the sum of the elastic and plastic part D = ΣA = A _elast + A _plast can be determined. A highly plastic material is called ductile.

When specifying the elongation at break and the tensile strength to different Magnesium alloys make it clear that the elongation at break is often all the higher can take if only medium high tensile strength values are reached and that conversely, only medium-high values of elongation at break with high values of tensile strength be achieved. Very high values of tensile strength can only be achieved by comparison reach low elongation at break values.

The elasticity denotes the elastic part of the stress-strain diagram according to Hook's law, where with ideal linear-elastic relationships no permanent change in shape occurs.

Furthermore, the yield point ratio V can be specified as the ratio of the yield stress F = R _P02 to the tensile stress Z = R _m . This results in two values for the largely uniaxial load that characterize the elasticity, two the plasticity and two their relationship to one another. The ratio of the elastic to the plastic part of the stretch gives the best approximation to reality.

The impact work is above all a measure of the energy consumption of a semi-finished product and for plastic behavior, i.e. for deformability and rate of deformation. A high impact work is therefore essential for the use of deformation elements such. B. Crash elements, impact absorbers, impact shields and impact carriers. The impact work - measured on notched samples - is u. a. due to higher absolute values for Magnesium alloys more meaningful than the impact energy and affects one largely uniaxial load. The impact work, which is always on notched samples is determined also indicates the susceptibility of a material to triaxial failure Burden. Their informative value is particularly low if the execution of the Notch significantly affects the values of the impact energy. The blow job and the Impact energy is measured under dynamic load and can be an indication give up on energy absorption and deformability. Tensile and compression tests are carried out in the Comparison under quasi-static loads. A conclusion from uniaxial on Multi-axis properties or relationships are only partially possible.

The values listed below measured on samples in a particular The state of manufacture therefore reflects the current material properties. she provide an indication of the forming behavior that previously occurred during the forming process was. In this state it is a conclusion about the properties and behavior of a person Semi-finished product or even a component with this semi-finished product, which may be further refined later use possible. Furthermore, there is a conclusion about the material properties formed alloys possible, the z. B. by bending, pressing, pressure rolling, Stretch drawing, deep drawing, hydroforming or roll forming processed semi-finished products are to be shaped. Because the change in Material properties from cast to extruded condition similar to that Change in material properties from cast to forged, rolled or a similar reshaped state is therefore also an inference to one other forming condition possible.

The use of lightweight components is usually based on the elastic Properties (stiffness) lifted, as far as it is not such. B. in an accident on the Deformation properties and thus on the energy absorption of the element and on the plastic behavior arrives. Therefore, regarding the u. U. multiple forming  especially the plastic ones and for the use the plastic ones and / or elastic ones Properties matter. These properties are typically for use on the respective ambient temperature, in extreme cases in the range from -40 ° C to + 90 ° C individual places in the vehicle or plane, however, to the locally lower or higher ones Turn off temperatures. However, the load state is usually multi-axis. The Conclusion from uniaxial to multiaxial loading conditions is all the more possible, ever more of an isotropic structure.

For the manufacture of such automotive elements, the manufacture is particularly suitable by die casting or extrusion, forging and / or rolling. requirement for the use of semi-finished products made of magnesium alloys or from them or with them Components manufactured in automobiles can meet certain property profiles depending be after application such. B. in deformation elements, seating and. Door frame one Tensile strength of the light material of at least 100 MPa, preferably at least 130 MPa, together with an elongation at break measured at room temperature of at least 10%, preferably at least 15%. The higher the tensile strength, Elongation at break and other properties due to high ductility and energy absorption point out, the more suitable these semi-finished products or components are generally for the Commitment. Furthermore, higher strength values and higher ductility are also one Relief and partly also a prerequisite for the forming of cast blanks or for the further forming of already formed blanks or semi-finished products. The higher these properties are as cast, the higher these are usually even in the deformed state. A higher ductility can the forming or the renewed Forming, especially extrusion, easier. Therefore an elongation at break of at least 10% also for the subsequent manufacturing steps to form elements Magnesium alloys helpful. Therefore, tensile strength of at least 150 MPa measured at room temperature, preferably at least 180 MPa, or an elongation at break of at least 18%, preferably of at least 20%, particularly preferred of at least 25%, recommended. Usually this is Elongation at break in the commercially available magnesium alloys measured at Room temperature less than 12%.

With stronger substitution of other alloys by magnesium alloys to by Weight savings to save fuel or the installation of additional elements without  Allowing weight gain is the advancement of the technology of the well-known Magnesium alloys and research into other magnesium alloys necessary especially with regard to the combination of properties ductility-strength.

Basically, there are various options for increasing the ductility and thus the elongation at break in magnesium alloys and related lightweight materials:

• 1. A very limited possibility of this increase results from the optimization of the Manufacturing process in connection with heat treatment processes and / or over optimized manufacturing parameters e.g. B. in extrusion. However, it is important when forming e.g. B. by extrusion that the dynamic recrystallization occurring is not Coarse grain formation leads. Because the energy consumption and the mechanical properties of an alloy should generally be larger the smaller the average grain size is. The goal of alloy development can be a modification of the structure by forming temperature-stable precipitates and / or stabilization the structure by influencing the grain growth to be as fine a grain as possible and to produce the lowest possible porosity.
• 2. When the crystal structure of the Mg main phase changes from the hexagonally closest Ball packing on the cubic body-centered crystal structure z. B. due to a higher Adding a doping element such. B. at least 10.8 wt .-% Li, without further doping elements a homogeneous β-lithium-magnesium mixed crystal produce an improved elongation at break and better formability Room temperature due to an increased number of sliding systems. Indeed strength and corrosion resistance may deteriorate.
• 3. Since grain boundaries and other structural inhomogeneities or structural defects such. B. Inclusions, pores, coarse deposits, oxide streaks and segregations in the Movement of dislocations can act as barriers, a refinement of the structure, a reduction in structural inhomogeneities / defects or an avoidance certain structural inhomogeneities / defects to increase the strength, the Elongation at break and energy consumption. The connections are however in Very complex in individual cases. Grain refinement is an important tool for more To activate deformation systems that slide grain boundaries and new flow processes allow at room temperature and thus improve ductility. This can be done through the Adding grain-fine additives or / and through heterogeneous nucleation during solidification of cast materials made of alloys with certain additives.

Even the commercially available Mg casting alloys or wrought magnesium alloys are in the cast and, if necessary, subsequently formed, in particular extruded, pressed, rolled or / and forged and if necessary thereafter heat-treated condition Usually previously relatively low ductility and low Energy absorption. For the inexpensive manufacture of semi-finished products, in particular for vehicles and airplanes, there is a need for suitable alloys and simple ones Process for the production of magnesium alloys with somewhat increased strength and greatly increased ductility.

Since the interest in wrought magnesium alloys has only increased somewhat in recent years So far, only a limited number of alloys are available for large-scale use to disposal. These are alloys based on Mg-Al-Zn such as B. AZ31, AZ61, AZ80 and AZ81, based on Mg-Zn-Zr such as B. ZK40 and ZK60 or on is the extrusion of Magnesium alloys hardly used.

Haferkamp, Bach, Bohling & Juchmann (Proc. 3 ^rd Int. Magnesium Conf. Manchester April 10-12, 1996, The Institute of Materials, London 1997, ed .: GW Lorimer) or Haferkamp, Bach & Juchmann ("Stand und Development trends of density-reduced magnesium materials ", lecture at the advanced training event Magnesium - Properties, Applications, Potentials" of the German Society for Materials Science Clausthal-Zellerfeld 1997) describe lithium-containing magnesium alloys based on MgLi without and with Al, AlZn, Ca, Si, SiCa, AlCa, CaAlZn or SiAlZn. For the elongation at break or tensile strength, values for MgLi40at% Al6at%, for example of 19% or about 260 MPa, and for MgLi40at% 42% or about 134 MPa are given Trials used small laboratory extrusion press, however, the forming speed and the degree of forming were low.

Furthermore, Haferkamp, Bach, Bohling & Juchmann at the Magnesium Conference in Garmisch-Partenkirchen 1992 (Magnesium Alloys and Their Applications, Eds .: B. L. Mordike & F. Hehmann, Oberursel 1992, 243-250) values of elongation at break and Tensile strength carried forward, that of MgLiAl, possibly with Zn, up to 25% and 239 MPa led.  

NASA report N67-22072, SP-5068, Properties and current applications of magnesium lithium alloys, 1967, indicates possibilities for increasing the strength of those containing lithium Magnesium alloys and reports on singular values of high elongation at break or high tensile strength, but it can be assumed that the usual at that time Manufacturing process and available raw materials high Impurities occurred that greatly influenced the result in this regard and Corrosion resistance compared to today's high-purity alloys significantly impaired.

The August Dow Chemical Company Magnesium Wrought Products publication 1994 gives an overview of commercially available extruded magnesium alloys. The The greatest elongation at break is given here for AZ61 with typically 17%.

Neite describes in Materials Science and Technology, Vol. 8, ED .: K. H. Matucha, 199 ?, in Chapter 4.3.2 Manufacturing processes and mechanical properties of typical Magnesium alloys. For extruded magnesium alloys based on AZ in shape of bars - especially increasing with the aluminum content - tensile strengths of 204 up to 340 MPa and elongations at break of 9 to 17% indicated by an artificial Aging could be increased up to a tensile strength of 380 MPa, but the Elongation at break decreased to 6 to 8%. For AZ31 250 MPa and 14 to 15% are given. Alloy M1 typically had a tensile strength in the extruded state 225 MPa and an elongation at break of 12%.

GB 2,296,256 A gives values of elongation at break of 17.2 and 18% for alloys MgAl0.5-1.1MnO.10-0.12, which, however, had a rather low flexural strength.

Kamado et al. describe in Proc. 3 ^rd Int. Magnesium Conference April 10-12 1996, Manchester / UK, Ed .: GW Lorimer, for the Al10Si1Ca0.5 alloy values of about 170 MPa tensile strength and 2% elongation at break for the press-molded state.

By J. Becker, G. Fischer and K. Schemme, Ught weight construction using extruded and forged somi-finished products made of magnesium alloys, lecture Wolfsburg 1998 values of 250 MPa for the magnesium alloy AZ31 in the extruded state Tensile strength and 14% elongation at break are communicated for the alloy M2 of 250 MPa for the  Tensile strength, but only 4% for the elongation at break. The samples were therefore not up ductile material properties optimized.

In US 3,419,385 the tensile strength for individual extruded magnesium alloys with contents of Y, Zn and Zr with 248 to 352 MPa and the elongation at break with 14 to 26% each specified by composition. The chemically closest to the alloy ZE10Zr0.7 The upcoming alloy Zn2.1Y1.9Zr0.9 only showed an elongation at break in the cast state from 8% to. It can be assumed that with the then usual manufacturing processes and available raw materials, high levels of contamination occurred Result strongly influenced in this regard and the corrosion resistance compared to significantly impaired the high-purity alloys that can be produced today.

There was therefore the task of a method for extruding Magnesium alloys with increased ductility and, if possible, increased energy consumption, Compressive or tensile strength and toughness by selecting the for these purposes propose the most effective parameters that have the lowest possible density and can also be produced as simply and inexpensively as possible.

The object is achieved with a method for producing a magnesium alloy high ductility u. a. by extrusion, which is characterized in that the Alloy with a degree of deformation of at least 1.5 is extruded that they are additives or traces of Cd less than 1.8 wt% and traces of up to 0.1 wt% Cu, up to 0.05 wt .-% Fe and up to 0.005 wt .-% Ni may contain that they contain Li in Range of 0.5 to 20 wt .-% contains that in addition to the contents of Mg and Li and optionally Al or / Lind Si contains at least one further chemical element of contains at least 0.1 wt .-% and that they have an elongation at break after extrusion of at least 20%, a compressive strength of at least 300 MPa and impact work measured on notched specimens of at least 70 J. This other chemical Element is preferably Mn, Zn and / or at least one rare earth element SE including La and Y. The magnesium alloy preferably has a Li content in Range from 3 to 18 wt .-% Li, preferably from 6 to 14 wt .-% Li. This broad The range of the lithium content covers both the material properties interesting 2-phase area with the hexagonal and cubic phase, as well as the  Krz phase range from essentially only the cubic phase as the U-containing phase occurs. A tensile strength of at least 150 MPa is particularly advantageous.

The object is further achieved with a method for producing a Magnesium alloy of high ductility u. a. by extrusion, in which the alloy with a degree of deformation of at least 1.5 is extruded, being additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and may contain up to 0.005% by weight of Ni, having a Ca content in the range of 0.1 to 6% by weight and after extrusion an elongation at break of at least 16%, a compressive strength of at least 300 MPa and impact work measured on has notched samples of at least 50 J. More advantageous in a variant In embodiments, the weight fraction of the Ca contained is in the range from 2 to 30%, preferably in the range of 5 to 20% by weight of the aluminum contained or if there is no aluminum on manganese. The Ca content is in particular 0.15 up to 4% by weight, preferably 0.2 to 1.5% by weight. The proportion of Ca can be partly determined by Sr be replaced, even if Sr usually behaves differently from Ca.

The task is also solved with a corresponding method, in which the Magnesium alloy contains Sr in the range of 0.1 to 6 wt .-% and after Extrusion measured an elongation at break of at least 17.5% and impact work on notched samples of at least 50 J. More advantageous in a variant Embodiments is the weight fraction of Sr contained in the range of 2 to 30%, preferably in the range of 5 to 20% by weight of the aluminum contained or if there is no aluminum on manganese. The Sr content is in particular 0.15 up to 4% by weight, preferably 0.2 to 1.5% by weight. The proportion of Sr can be partly determined by Ca to be replaced.

The task is also solved with a corresponding method, in which the Magnesium alloy has a Zr content in the range of 0.1 to 10 wt .-% and after Extrusion has an elongation at break of at least 18%, a compressive strength of at least 300 MPa and impact work measured on unslotted samples of has at least 20 J. The Zr content is in particular 0.15 to 6% by weight, preferably 0.2 to 3% by weight, particularly preferably 0.3 to 1.5% by weight.  

The task is also solved with a corresponding method, in which the Magnesium alloy including at least one rare earth element SE La and Y in the range of 0.1 to 10% by weight in total and one after extrusion Elongation at break of at least 18%, a compressive strength of at least 300 MPa and has an impact energy measured on notched specimens of at least 50 J, where the total content of rare earth elements in alloys with lithium only up to Is 1% by weight. The total content of SE in alloys with lithium added in particular 0.15 to 0.9% by weight, preferably 0.2 to 0.8% by weight, particularly preferably 0.3 up to 0.75% by weight. For magnesium alloys without the addition of lithium, the total content is of rare earth elements, in particular 0.15 to 8% by weight, preferably 0.2 to 6% by weight, particularly preferably 0.3 to 4% by weight, very particularly preferably 0.4 to 3% by weight.

It has been shown that the modification of grain sizes and phase distributions the alloying of accompanying elements such as lithium, zirconium, rare earth elements SE such as e.g. B. cerium, praseodymium, neodymium, samarium, gadolinium, ytterbium, yttrium and lanthanum or their mixtures or the alkaline earth metals - especially Ca, Sr, Ba - is helpful under Production of significantly stronger and / or more ductile magnesium alloys. First of all Addition of lithium, calcium, strontium, zirconium or at least one Rare earth element including yttrium and lanthanum has proven to be beneficial Further development of magnesium alloys proven.

The object is further achieved with a method for producing a Magnesium alloy of high ductility u. a. by extrusion, the thereby is characterized in that the alloy is dynamically recrystallized during extrusion, that they have additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight Cu, up to 0.05 wt .-% Fe and up to 0.005 wt .-% Ni may contain a Magnesium alloy based on AM, AS, EM, EZ, MA, ME, SA, ZA or ZE and that it is after extrusion, an elongation at break of at least 17.5%, a compressive strength of at least 300 MPa and impact work measured on unslotted samples of has at least 45 J.

The task is also solved with a corresponding method, in which the Magnesium alloy based on AZ with at least one addition of Ca, Sr, Li, SE or / and Zr is in each case at least 0.1% by weight and in which it is one after extrusion  Elongation at break of at least 17.5%, a compressive strength of at least 350 MPa and has an impact energy measured on notched specimens of at least 50 J. The The proportion by weight of the respective additive can in particular be 0.15 to 6% by weight, preferably 0.2 to 4% by weight, particularly preferably 0.25 to 2% by weight. In addition, other additions can occur, preferably those that are dynamic Recrystallization behavior and fine grain influence.

The task is also solved with a corresponding method, in which the Magnesium alloy based on MN with at least 1% by weight Mn and with the addition of Ca, Sr, Li, SE or / and Zr each of at least 0.1 wt .-% and in which they according to Extrusion has an elongation at break of at least 15%, a compressive strength of at least 300 MPa and impact work measured on unslotted samples of has at least 20 J. The Mn content is preferably at least 1.3% by weight. The proportion by weight of the respective additive can be in particular 0.15 to 6% by weight, preferably 0.2 to 4% by weight, particularly preferably 0.25 to 2% by weight. In addition, other additions can occur, preferably those that are dynamic Influence recrystallization behavior.

The task is also solved with a corresponding method, in which the Magnesium alloy based on MZ or ZM, which is an addition, in particular of Ca, Sr, Li, SE or / and Zr can each contain at least 0.1 wt .-%, and in which they after the extrusion has an elongation at break of at least 15%, a compressive strength of at least 300 MPa and impact work measured on unslotted samples of has at least 40 J. The alloy preferably has one after extrusion plastic part of the tension determined in the tensile test according to the stress-strain Diagram from the difference between tensile stress and yield stress of at least 40 MPa on.

The remaining contents of the chemical composition mentioned exist predominantly or essentially of magnesium. Levels of cadmium interfere with the Processing only because of their toxicity, but are otherwise particularly with regard to Formability is an advantage. Traces of copper, iron and nickel should be as possible be low since they affect the processing and / or the material properties impact.  

It has been shown that usually high with the ductile magnesium alloys Extrusion speeds can be achieved. There are still tests no effort has been made to achieve the highest extrusion speeds achieve, but rather there is a clear potential, even significantly higher To be able to reach speeds. The degree of deformation characterizes the degree of Reduction of cross-section during forming and is considered the natural logarithm of the Ratio of initial cross-section to cross-section specified after forming. He is therefore often correlated with the degree of dynamic recrystallization, where possible not a stronger growth of individual grains should occur, but one if possible fine-grain structure is sought, which is high for some magnesium alloys Ductility conditional. The more stable the structure of a magnesium alloy, the more fine-grained the structure becomes or remains when forming. It has also been found that the degree of deformation is advantageously at least 1.5, preferably at least 2, particularly preferably at least 2.5. If the degree of deformation is less than 1.5, the dynamic Very little recrystallization during forming. It would also have a grade of 3.5 or more can be selected in the tests. The extrusion speed is advantageously at least 1.5 m / min. preferably at least 2.5 m / min. particularly preferably at least 5 m / min. very particularly preferably at least 7.5 m / min. It is above all due to the decreasing quality of the extruded profiles limited.

It is necessary that the magnesium alloy is selected from the group of Magnesium alloys due to the dynamic recrystallization and fine grain get a higher ductility. The dynamic recrystallization and structural change from the preformed or compacted molded body to the finished semi-finished product, component or Composites are often not created solely by extrusion and the associated processes thermal or mechanical influences, but they are preferred performed essentially or even mainly in extrusion.

The task is finally solved with a semi-finished product made of a magnesium alloy or with a component made of it or with it or with a composite with a such semifinished product or component that was produced according to the invention.  

The semifinished product or component according to the invention preferably consists essentially of a magnesium alloy selected from the group of alloys based AM, AS, AZ, EZ, MA, SA, ZA or ZE with added lithium, EM, EZ, ME, MN, MZ, ZE and ZM Containing at least one rare earth element AM, AS, AZ, MA, MN, MZ, SA, ZA or ZM with calcium or / and strontium addition or EZ, MN or ZE with zirconium addition.

For the purposes of this application, semi-finished products are understood to be shaped articles which have not yet are finished and ready for use for their respective application. As components on the other hand, the molded articles are suitable for the intended purpose designated. However, both terms flow smoothly into one another, since it is the same shaped body for one purpose around a semi-finished product, but for the other can already be a component. Furthermore, for the sake of linguistic Simplification does not strictly differentiate between semi-finished products and components throughout the text or both mentioned at the same time or only spoken of magnesium alloy, although both can be meant.

The semifinished products made from magnesium alloys according to the invention or from them or with them manufactured components or composites can be used as frame elements, Elements of the vehicle cell or vehicle outer skin, as a vehicle cell or Vehicle outer skin, cockpit support, cockpit skin, housing, floor element, floors, cover, Tank elements, tank flaps, brackets, supports, beams, angles, hollow profiles, pipes, Deformation elements, crash elements, crash absorbers, impact absorbers, impact shields, Impact beams, small parts, as a welded profile construction, for the vehicle body, for Seat, window or / and door frames, as semi-finished products, components or composites on or in Automobile or airplane.

Process for the production of extruded profiles

The magnesium alloys, especially the lithium or calcium, strontium, Zirconium and / or magnesium alloys containing at least one rare earth element, which can be reshaped according to the invention by extrusion molding are produced in two patent applications filed by the same applicant in detail on the same day described; those registrations are considered to be in their entirety by name Registration included.  

It is preferable to start from high-purity, commercially available alloys. Possibly. these alloys are alloyed with additives. The high-purity alloys can absorb small amounts of contaminants from the crucible during the melting process. The alloys can, for example, in a nickel and chrome-free steel crucible under a protective gas atmosphere, for. B. Ar or / and SF ₆ , are melted. Instead of a casting process, the powder-metallurgical production of green compacts, possibly with subsequent annealing, can also be used. The process steps are known in principle, but require a different modification or optimization depending on the alloy.

Prerequisite for the further processing of magnesium alloys by extrusion, Rolling and / or forging is the production of suitable materials such. B. in the form of Blocks, bolts or slabs. There are for the production of bolts for extrusion two main options:

In the first method, a bolt with a very large diameter can be cast are then turned into round bolts using a high-performance extrusion press can be pressed with a diameter that corresponds to the recipient diameter. The segregation is reduced by the thermomechanical treatment.

A less complex process than this double extrusion is the production of the Bolts by sand, mold or continuous casting with a sufficiently large size Machining allowance. However, it is important to ensure that there are no severe segregations occur that are not or insufficient due to long homogenization times be balanced. Otherwise, the consequences could be poor compressibility and greater dispersion of the mechanical properties, in particular the ductility.

The cast bolts can first be subjected to heat treatment depending on the Alloy composition in z. B. 350 ° C in the range of 6 h to 12 h homogenized to eliminate segregations in the structure that z. T. heterogeneous structure too improve and increase the pressability. Then the homogenized bolts machined to the required dimensions.  

Segregations can lead to uneven deformation and critical Extrusion conditions lead to cracks or local melting, which is bad Surface qualities can cause. With less well homogenized bolts is a unnecessarily high pressure required for extrusion. The homogenized bolts are then prepared for extrusion.

The extrusion of the magnesium alloys can be carried out in the same extrusion plants take place, which are used for the extrusion of aluminum alloys, both via direct as well as indirect extrusion. Only with the Tool design (die), the deformation behavior must be specifically taken into account. There are sharp-edged inlets, such as those used for aluminum alloys Avoid magnesium alloys, otherwise there is a risk of surface cracks. In many cases z. B. for matrices of round profiles an entry angle of approx. 50 ° for Magnesium alloys used. A round profile was used in the tests.

The most important parameter besides the extrusion temperature is the extrusion speed because it affects the properties and surface quality of the Extruded profiles significantly influenced. A high pressure also means a high one Extrusion speed, which is sought for economic reasons. A high Extrusion speed is usually with an even better surface quality connected. The extrusion speed is very different from the geometry of the strand dependent. The pressability of the magnesium alloys is comparable to that heavy-duty aluminum alloys. A high extrusion speed is true Aimed from an economic point of view, this is not the case with magnesium alloys always feasible. It can also be used at particularly high extrusion speeds there are no cracks or burning of the magnesium alloy. In addition, the Degree of deformation of great importance. It goes along with the change in the structure. Of therefore a high degree of forming is advantageous. However, it is not allowed with high degrees of deformation local melting occurs. Despite certain knowledge of the extrusion of Magnesium alloys usually need the parameters for extrusion in detail be worked out because there is a huge potential for optimization.

The extrusion can advantageously be followed by a heat treatment. This heat treatment is particularly suitable for the lithium-containing alloys of  Interest, while the other extruded modified according to the invention Alloys cannot be greatly improved by this heat treatment. The semi-finished products can be directed if necessary, e.g. B. by bending, pressing, pressure rolling, stretch drawing, deep drawing, High pressure forming or roll forming further deformed, e.g. B. by cutting, drilling, Milling, grinding, lapping, polishing machined, joined and / or z. B. by etching, pickling, Painting or other coating are surface treated. With the Alloys according to the invention can be solid and extruded profiles in simple or complicated cross sections can be extruded without problems. Here you can Semi-finished products are improved or components can also be produced therefrom or with them.

When joining, the semi-finished product or the component made therefrom or with it can pass through at least one low-heat joining process such. B. gluing, riveting, plugging, pressing, Pressing in, clinching, folding, shrinking or screwing and / or at least one heat-generating joining process such. B. composite casting, composite forging, Composite extrusion, composite rolling, soldering or welding, in particular Beam welding or fusion welding, with a similar or different type Semi-finished product or component can be connected. The different semi-finished product or component can likewise essentially of a magnesium alloy or of another alloy or also consist of a non-metallic material. It can be the same or one have a different geometry than the semi-finished product or component according to the invention. The Joining methods can serve in particular to create a housing from several elements, to manufacture an apparatus, a system, a profile construction and / or a cladding.

Examples

The following examples according to the invention represent selected embodiments, without restricting the invention.

In the alloy designations used, A Al, E indicates at least one Rare earth element SE, whereby Y is also counted among the rare earth elements, M or MN Mn, S Si and Z Zn - usually with content in% by weight, unless otherwise is noted. With commonly used alloy information such. B. AZ31 will be through the numbers, as usual for the respective alloy, only in the order of magnitude specified, which can vary to a relatively wide extent, as is customary in the industry. In addition, at  the starting alloy used in the examples and the ones produced with it modified alloys based on AZ have a low manganese content. All Examples showed traces of less than 0.1 wt% Cd, less than 0.05 wt% Cu, less than 0.04 wt% Fe and less than 0.003 wt% Ni.

The alloys were classified as high purity alloys or commercially available usually made of high-purity starting alloys such. B. AM, AS or AZ alloys or by adding high-purity magnesium HP-Mg, a rare earth element-containing one Master alloy with a ratio of Nd to other rare earths including yttrium of 0.92, a zirconium-containing master alloy and / or calcium or strontium alloyed. The standard alloys contained an Mn content of up to about 0.2% by weight. The alloys were in a steel crucible under the protective gas atmosphere of an Ar-SF6 The mixture melted. The casting of those required for the subsequent extrusion Blanks were made in a cylindrical steel mold with machining allowance. The achieved Element contents were checked spectroscopically. With all alloys was on it ensured that the structure of the cast body is as homogeneous and free of contamination is because this can affect ductility sensitively. All alloys could be made without Melt problems, drain and process into bolts.

The bolts were then turned to a diameter of 70 mm and to a length of 120 mm brought. The bolts were then subjected to homogenization treatment at e.g. B. 350 ° C exposed for 4 h or 12 h to eliminate segregation in the structure and the Increase pressability. Segregations can lead to uneven deformation and critical extrusion conditions lead to cracks or local melting, which can cause poor surface qualities. With less well homogenized bolts an unnecessarily high pressing pressure is required during extrusion. The homogenized bolts were then well prepared for extrusion.

The homogenized bolts were then brought up to the respective extrusion temperature heated, warmed up and directly in a 400 t horizontal press Extrusion process extruded. The temperature of the bolt is the temperature which the bolt has when it enters the extrusion press.  

The suitable ones were tested in systematic preliminary tests on the AZ31 reference alloy Extrusion parameters selected; on the extruded samples mechanical properties and the average grain sizes determined (Tables 1 and 2). The results of the preliminary tests essentially determined the test parameters of the subsequent attempts.

During the actual tests, several of the manufacturing parameters were systematically varied (Tables 3e / f and 4e / f). On the one hand, the die diameter was varied and were the die speed and extrusion temperature kept constant, on the other hand, the matrix geometry was kept constant and became the Die speed varied and finally the extrusion temperature varies depending on the alloy. The ram speed and the extrusion ratio gave the extrusion speed. With the help of such a parameter matrix an assessment of the influence of different forming conditions was possible.

All alloys, both the starting alloys and those by additives modified alloys could easily be used in a wide temperature, Form extrusion speed and extrusion ratio range. Bolts showed a good compressibility with a large scope in terms of pressing force and Pressing speed. The extrusion speed was not yet in the tests maxed out to the highest possible speeds and therefore can still generally be significantly increased. The lower extrusion temperature is due to the insufficient plastic deformability below a temperature in the range of about 200 to 220 ° C. conditionally, the upper extrusion temperature is limited by the proximity to eutectic temperature and possibly through the initial formation of portions of a molten phase.

Depending on the extrusion conditions, the same result Alloy composition Differences in the structure of the samples. The occurred Extrusion pressures varied depending on the alloy used and the set one Extrusion parameters. Generally, a dynamic one occurred during extrusion Recrystallization, depending on the extrusion parameters and the Alloy composition led to different average grain sizes. The The composition of the magnesium alloys varied only slightly or almost not at all  from the composition of the melt to the composition before or after Extrusion to the composition of the semi-finished product made from it. The The semifinished product or component according to the invention preferably consists essentially of a Magnesium alloy, which is selected from the group of alloys based on AM, AS, AZ, EZ, MA, SA, ZA or ZE with added lithium, EM, EZ, ME, MN, MZ, ZE and ZM with one Content of at least one rare earth element AM, AZ, MA, MN, MZ, ZA or ZM Calcium or / and strontium additive or EZ, MN or ZE with zirconium additive.

The strength values determined on the cast and extruded samples were much higher than expected. The deformability was also surprising of these alloys very high. It was also surprising that the material properties of the modified alloys surprisingly little depending on the Extrusion conditions varied, which is advantageous for manufacturing. It was further Surprisingly, the impact energy of the ZE10 alloy was so high.

Finally, the course of the extrusion that varied the course of the extrusion in the Characterized path diagram for alloys AZ, AZLi3.6 and AZLi6.8 with increasing lithium content differently than expected: it was shown with low lithium Addition worse behavior than without or with a higher lithium content. Some of the Alloys containing lithium gave an unexpectedly strong result with a high lithium content Dependence of the material properties on the type of heat treatment.

The extruded round profiles were processed by milling and turning into round specimens (d ₀ = 5 mm, I ₀ = 5.d ₀ , small proportionality bar, according to DIN 50 125), pressure tests (d ₀ = 10 mm, I ₀ = 2.d ₀ , according to DIN 50 106), impact bending tests (10 × 10 × 55 mm, according to DIN 50 116) and notched impact bending tests (according to DIN 50 lf 5). 5 of these samples were produced and tested per alloy and test. For all samples, the longitudinal direction was chosen so that it coincided with the direction of extrusion.

In the tensile test, tensile strength R _m , yield strength = yield strength R _P0.2 and elongation at break A or z. T. also determined the constriction of fracture in the tensile test at a tensile speed of 0.5 mm / min. Values of the compressive strength R _Dm , compression limit R _D0.2 and compression A _D at a printing speed of 0.5 mm / min were obtained in the compression test. The beginning of the plastic deformation (expansion or compression limit) was determined graphically. Brinell hardness measurements were also carried out in accordance with DIN 50351. All measurements took place at room temperature. The results of the mechanical determinations are summarized in Tables 3a-c and 4a-c and those of the structural examinations in Tables 3d and 4d.

Grindings were made on selected samples, with respect to average grain size, Structural inhomogeneities as well as the type and distribution of the separated phases contained were assessed. This evaluation was used to further optimize the Manufacturing and processing parameters.

The variation of the extrusion parameters had a different influence on that Property profile of the extruded magnesium materials. Tendencies of Material properties of the different alloys depending on the manufacturing parameters can be seen from Tables 3e / f and 4e / f.

The measurement results of the Brinell hardness determinations did not allow any special ones Statement. The Brinell hardness of the extruded samples was 7 to 22% higher than the cast samples. The hardness increased with the aluminum content.

A) Li-containing magnesium alloys

Production of the bolts: casting in tube molds at a casting temperature of 680 to 720 ° C for larger diameters and turning to usually 70 mm in diameter. The turned bolts were heat-treated at 350 ° C for 4 h (= homogenized).

Extrusion: Depending on the sample, an extrusion temperature in the range of 150 to 300 ° C and a time in the range of 50 to 110 min was set for heating and heating the bolt. Preliminary tests were carried out with the reference alloy AZ31 (Tables 1 and 2). The preliminary tests allowed the preselection of the test parameters. The specific extrusion tests were carried out in a 400 t extrusion press with direct extrusion. Depending on the sample, with a recipient diameter of 74 mm, a recipient temperature in the range from 180 to 259 ° C., a die diameter in the range from 15 to 18 mm, a compression ratio A / A ₀ in the range from 16.9 to 24.3, a degree of deformation ϕ = In (A ₀ / A) in the range from 2.8 to 3.2, a stamp speed in the range from 191 to 419 mm / min. an extrusion speed in the range of 3.2 to 9.0 m / min. a compression pressure at the start of the extrusion in the range from 15.2 to 24.3 MPa and a compression pressure at the end of the extrusion in the range from 10.0 to 14.8 MPa. Stubbornly a small part of the experiments are shown in Table 3f.

The influence of extrusion parameters on the material properties of those containing lithium Alloys and their undoped base alloys were limited. He was with the Tensile strength was particularly low and increased beyond the elongation at break and compressive strength something to do with the work.

The extruded AM20Li3.6 alloy showed in comparison to the extruded alloy AM20 sometimes has higher mechanical properties (Tables 3a / c). Like the other extruded alloys, the addition of lithium led to a very strong one Increase in field work. The extruded AM20 alloy had a very high one elastic and a comparatively very low plastic part of the tension in the extruded state (Table 3b). The addition of lithium doubled the corresponding plastic proportion.

The AZ31Li3.6 alloy was not subjected to tensile tests when cast characterized because the porosity of the samples was still a bit too high to be characteristic To provide statements. In the extruded state, this alloy had the highest Compressive strength values. With the AZ31 alloyed with lithium significantly higher toughness on notched impact samples as well as significantly higher Elongations at break determined as on the associated samples not alloyed with lithium, the highest values for the essentially two-phase alloy AZ31Li12.3 occurred. In contrast, the tensile strength decreased with the lithium content. The compressive strength was for the samples in the as-cast state proportional to the lithium content, for extruded ones However, samples are highest at medium lithium levels. Among the alloys in the The AZ31Li6.8 alloy showed an astonishingly high mean value at 122 MPa the yield strength. The deformability of the base grid of the AZ31 was Addition and the possibly modified elimination phase increased. The alloy AZ31Li6.8 showed, compared to the alloy AZ31 Li3.6, a reduced tensile and Compressive strength, but a high compression limit and high elongation at break. The The addition of lithium improved the formability.  

This had an effect on the lithium-containing alloys and their starting alloys Stress under pressure is different from that under tension: different from tensile strength took the compressive strength and sometimes the compression limit from AZ31 the lithium content of the AZ31Li3.6 alloy. The alloy AZ31Li6.8 showed due their high lithium content compared to the average of all samples in this series Mean values (Table 3a) the highest compression limit and fracture compression and a very high one Compressive strength. In this series the fracture compression of the samples was in the cast Condition higher than that of the extruded samples.

The cast alloy ZE10 had a very low elastic content, but almost on average high plastic part of the tension. With a lithium additive the elastic part increases significantly. On the other hand, the ZE10 alloy won at Extruding an extraordinarily high elastic portion of the tension during the plastic content remained approximately constant. For the alloys ZE10 and ZE10Li3.7 increased all mechanical properties of cast samples with the lithium Content drastically. For the corresponding extruded samples, the mechanical properties with the exception of tensile strength and yield strength the lithium content. The alloy ZE10Li3.7 showed among the examined lithium containing magnesium alloys the highest values of the impact work, whereby due to Crash tests on deformation elements from the invention Magnesium alloys are assumed that the alloy MgLi15.5Al2.5Zn0.8 should have even higher impact and notch impact values than that Alloy ZE10Li3.7. Up to 140 J were obtained on individual samples of the ZE10Li3.7 alloy measured; other samples were taken through the abutment of the testing machine without to break completely, so that no measured value of the impact work could then be determined. The maximum applicable impact energy was 150 J.

The degree of deformation had a considerable influence on the impact work of those containing lithium Rehearse. The hammer work was with the lithium-containing magnesium alloys at one Degree of deformation ϕ of 2.83 often about 30 to 65% higher than for ϕ = 3.06 (Table 3f). At lower degrees of deformation and thus with smaller compression ratios resulted much higher values of impact work. This tendency occurred in the samples from unmodified Starting alloys and not or only with the samples alloyed with Ca or Zr weak on. The best impact work was performed on the samples containing lithium  Forming temperatures of 200 to 250 ° C achieved. The forming speed (= Extrusion speed) had little effect on tensile strength and elongation at break.

The pressure-pressure curves during extrusion of the lithium-containing alloys at 200 ° C showed that with the alloy AZ31 + 12at% Li as well as AZ31 only with a higher one Pressing pressure, about 16 MPa, a flow of the material of the bolt occurred compared to the alloys AM20 + 12at% Li, AZ31 + 21at% Li and ZE10 + 12at% Li, in which the flow already occurred at around 12.5 MPa, but also a cheaper, lower pressure after a longer route was determined.

B) Ca, Sr, SE or / and Zr-containing magnesium alloys

Casting the bolts: The melt was at a temperature in the range of 780 to 820 ° C, once at 750 ° C, kept and cast. The shape showed depending on the experiment a diameter of 90 or 110 mm and a mold temperature in the range of 80 to 320 ° C. The element contents achieved were checked spectroscopically.

The castings were homogenized at 350 ° C. over 12 h. By turning bolts usually made 70 mm in diameter and 120 mm in length; with 6 samples of Alloy AZ31Ca0.3, however, was chosen to have a diameter of 74 mm. Depending on the sample was an extrusion temperature in the range of 200 to 450 ° C and a time to Heating and warming set in the range from 60 to 150 min.

Extrusion: Preliminary tests were carried out with the AZ31 alloy in a 400 t extrusion press direct extrusion carried out (Tables 1 and 2). With a The recipient diameter of 74 mm was successfully examined in a wide range of parameters become. The preliminary tests allowed the test parameters to be defined.

The specific extrusion tests were carried out in a 400 t extrusion press with direct extrusion. Extrusion temperature: 340 ° C, 365 ° C and 390 ° C respectively after 1 hour of heating and warming the bolt. Press dies with a diameter of 15, 16 or 18 mm and corresponding to a compression ratio of 1: 24.3, 1: 21.4 and 1: 16.9 were predominantly used. The pressing speed was 3.8-4, 5, 5.0-5, 5, 5.8-6.5 and 9.5-10 m / min. Only a small part of the extrusion tests are shown in Table 4f. Depending on the sample, with a recipient diameter of 74 mm, a recipient temperature in the range from 250 to 380 ° C., a die diameter in the range from 14 to 18 mm, a compression ratio A / A ₀ in the range from 16.9 to 27.9, a degree of deformation ϕ = In (A ₀ / A) in the range from 2.8 to 3.3, a stamp speed in the range from 145 to 508 mm / min. an extrusion speed in the range of 3.2 to 10.8 m / min. a compression pressure at the start of the extrusion in the range from 8.7 to 23.5 MPa and a compression pressure at the end of the extrusion in the range from 7.2 to 16.5 MPa and once from 23.3 MPa.

The parameter spectrum showed good compressibility with a large scope with regard to pressing force and pressing speed. The microstructure and the achieved Elongation at break correlated with the deformation parameters. There have been comparative high strength values achieved.

The extrusion pressures that occurred varied depending on the alloy used and set parameters in a wide range. The final pressures reached were for Alloys without Ca, Sr, SE or Zr addition in the range around 10 ± 2 MPa Extrusion temperatures greater than 300 ° C and for Ca, Sr, SE or Zr-containing alloys up to 4 MPa higher. Cause for the higher extrusion pressures and thus for the increased resistance to deformation of magnesium alloys with Ca, Sr, SE or Zr Additive is a higher proportion of stable excretions than with magnesium alloys without this addition. For lower temperatures, generally higher ones were used Extrusion pressures determined.

The tensile strength of the extruded (= extruded) alloy AM50 was at values up to 287 MPa, the compressive strength at values up to 365 MPa, the elongation at break at Values up to 21.6% and the impact work of notched specimens at values up to 85 J (Tables 4a / c). All of these material properties were therefore significantly higher than those were determined on samples in the cast state.

In the case of the extruded alloy AM20Ca0.2 or AM50Ca0.5, compared to extruded alloy AM20 or AM50 higher in pressure and impact tests mechanical properties with a comparably high ductility, with the lower Alloys containing aluminum also in tensile tests. Because the examined extruded samples that have not yet had the best structural homogeneity can be found here  even better properties can be achieved. For the extruded alloy AZ31Ca0.3 and AS41Ca0.4 the results of the compressive strength were higher than for the extruded AZ31 or AS41 alloy. With these Ca-modified alloys the highest determined compressive strengths occurred. In the case of extruded alloys AM50 and AZ31 trended the average grain sizes with the extrusion temperature e.g. B. in the range of 6 to 12 microns or 3.5 to 10 microns. The alloy was AM50Ca0.5 the average grain size in the range of 4.5 to 9 µm and therefore due to the addition of Ca. lower, the mean grain sizes proportional to the extrusion temperature also increased slightly.

With the extruded ME10 alloy, the highest values of the tensile tests were with the average tensile strength at values up to 336 MPa and the average yield strength at Values up to 327 MPa. The cast alloy ME10 showed a very high plastic part of the tension, while the ratio of the elastic to the plastic component during extrusion and reversed extreme values (Table 4b). Very small average grain sizes in the range from 3 to 5 µm occurred.

With the extruded alloy MN150Ca0.2 there was a very strong increase in most mechanical properties compared to the extruded alloy MN150 on. An addition of Zr0.7 to the extruded starting alloy MN150 only had an effect little out.

In the case of the extruded ZE10 alloy, there were fewer mechanical ones Properties determined, but these varied greatly with the temperature, so that still better mechanical properties can be achieved with an even higher temperature: The properties of the ZE10 alloy become essential from the rare earths influenced and can vary in the variation of rare earth elements including yttrium or their contents can be further optimized. Medium occurred with the ZE10 alloy Grain sizes in the range from 6.5 to 13 µm, which again with the extrusion temperature rather increased; however, this alloy heated up with increasing Extrusion speed relatively strong, which at higher extrusion speed also led to somewhat larger average grain sizes. With the extruded modified alloy ZE10Zr0.7 resulted very much due to the addition of zirconium higher strength than the ZE10 extruded base alloy. She pointed like that  additionally extruded alloy containing Zr0.7 very high values of elongation at break and the impact work. So when cooling aluminum-free zirconium containing melts use heterogeneous nucleation due to a Grain boundary pinnings led to a particularly fine structure. The hammer work on however, the notched specimen was due to the inhomogeneous distribution of the zirconium containing phase in comparison to the samples of the alloy ZE10 partially slight sunk. The zirconium additive stabilized the extruded ZE10Zr0.7 alloy the structure. During extrusion, microstructures with medium grain sizes arose Range from 2.2 to 4.5 µm. These small grain sizes were created over a wide range Extrusion parameter range. With this alloy, the slight variation was Grain sizes depending on the extrusion parameters are striking.

Adding RE0.7 to the extruded ZM21 alloy had little effect on the mechanical properties.

It has been found that the Hall-Petch relationship also applies to those of the invention Magnesium alloys in the trend is valid, according to the mechanical properties smaller grain sizes can be improved. In many cases, this applies especially to the train and Compressive strength, but also basically for elongation at break and impact work.

Magnesium alloys in particular were found to be suitable, in which a Ca content in the range of about 0.05 to 0.2% by weight Ca was added to each 1% by weight Al present in order to separate out the Al ₂ Ca phase to enable. The Al ₂ Ca phase proved to be more temperature stable than the Mg ₁₇ Al ₁₂ phase and was therefore able to hinder the grain growth during extrusion better than the Mg ₁₇ Al ₁₂ phase. The Mg ₂ Si precipitation phase also prevented grain growth during extrusion better than the Mg ₁₇ Al ₁₂ phase. The addition of Ca to Al-free alloys led to the formation of Mg ₂ Ca or Ca ₅ Zn ₂ precipitates. It was shown that the phase Mg ₁₇ Al ₁₂ , which normally appears in magnesium alloys containing Al, causes a somewhat increased strength, but is also responsible for a lower elongation at break. Since this phase is even more brittle than the pure hexagonal Mg phase, higher levels of Mg ₁₇ Al ₁₂ should be avoided.

Table 1

Results of the preliminary tests to determine the extrusion parameters with the AZ31 alloy at an extrusion temperature of 400 ° C, a die diameter of 16 mm, a recipient diameter of 74 mm and a compression ratio of 1:21

Table 2

Influence of the compression ratio on the average grain sizes and the mechanical properties from the tensile test at an extrusion temperature of 400 ° C in the preliminary tests to determine the extrusion parameters

Tables 3 and 4 mean "casting" = material in the as-cast state and "extr." = Casting material, which is then homogenized and extruded (extruded) was reshaped, "B" = example according to the invention and "VB" = comparative example the state of the art.

Table 3a

Average values of the measurement results of the mechanical tests averaged over the various samples of the lithium-containing magnesium alloys and their starting alloys

Table 3b

Mean values of the values that can be determined from the stress-strain diagram of the tensile tests for lithium-containing magnesium alloys and their starting alloys. F = R _P02 = yield stress = elastic part of the stress. V = yield strength ratio = F: Z, R _m = tensile stress Z = elastic + plastic part of the stress

Table 3c

Highest mean values of the measurement results of the mechanical properties selected from various individual samples of the lithium-containing magnesium alloys

3d table

Structural components in the as-cast state after homogenization at 350 ° C for 4 h or after extrusion as well as predominantly occurring grain sizes (* = before hot aging)

Table 3e

Process parameters and average grain size for lithium-containing magnesium alloys and their starting alloys

Table 4a

Average values of the measurement results of the mechanical tests on various samples of the Ca, Sr, SE and Zr-containing magnesium alloys and their starting alloys

Table 4b

Average values of the values that can be determined from the stress-strain diagram of the tensile tests for modified lithium-free magnesium alloys and their starting alloys. F = R _P02 = yield stress = elastic part of the stress. V = yield strength ratio = F: Z. R _m = tensile stress Z = elastic + plastic part of the stress

Table 4c

Highest mean values of the measurement results of the mechanical properties selected from various individual samples of the modified magnesium alloys

Table 4d

Mainly occurring grain sizes in the as-cast state after homogenization at 350 ° C for 4 h or after extrusion with the modified lithium-free magnesium alloys and their starting alloys

Table 4e

Process parameters for various samples of the modified lithium-free magnesium alloys and their starting alloys

Claims (22)

1. A process for producing a magnesium alloy of high ductility, inter alia by extrusion, characterized in that the alloy is extruded with a degree of deformation of at least 1.5, that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain Li in the range from 0.5 to 20% by weight contains that, in addition to the contents of Mg and Li and possibly Al or / and Si, it contains at least one further chemical element of at least 0.1% by weight and that after extrusion it has an elongation at break of at least 20%, has a compressive strength of at least 300 MPa and impact energy measured on notched specimens of at least 70 J. 2. A method of manufacturing a high ductility magnesium alloy and the like. a. by Extrusion, characterized in that the alloy with a Degree of deformation of at least 1.5 is extruded that they are additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05 % By weight of Fe and up to 0.005% by weight of Ni may contain a content of Ca in the range of 0.1 to 6% by weight and one after extrusion Elongation at break of at least 16%, a compressive strength of at least 300 MPa and impact work measured on unslotted samples of at least 50 J has. 3. Method for producing a magnesium alloy of high ductility u. a. by Extrusion, characterized in that the alloy with a The degree of deformation of at least 1.5 is extruded so that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05 % By weight of Fe and up to 0.005% by weight of Ni may contain Sr in the range of 0.1 to 6% by weight and an elongation at break after extrusion of at least 17.5% and impact work measured on unslotted samples of at least 50 J.   4. A method of manufacturing a high ductility magnesium alloy and the like. a. by Extrusion, characterized in that the alloy with a Degree of deformation of at least 1, 5 is extruded that they are additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05 % By weight of Fe and up to 0.005% by weight of Ni may contain Zr in the range of 0.1 to 10% by weight and one after extrusion Elongation at break of at least 18%, a compressive strength of at least 300 MPa and impact work measured on unslotted samples of at least 20 J has. 5. A method of manufacturing a high ductility magnesium alloy and the like. a. by Extrusion, characterized in that the alloy with a Degree of deformation of at least 1.5 is extruded that they are additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05 % By weight of Fe and up to 0.005% by weight of Ni may contain a content of at least one rare earth element SE including La and Y in the range of a total of 0.1 to 10 wt .-% and an elongation at break after extrusion of at least 18%, a compressive strength of at least 300 MPa and a Shows impact energy of at least 50 J measured on notched specimens, where the total content of rare earth elements in lithium-containing alloys is only up to 1% by weight. 6. A method of manufacturing a high ductility magnesium alloy and the like. a. by Extrusion, characterized in that the alloy during extrusion is dynamically recrystallized to have additions or traces of Cd less than 1.8 % By weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain a magnesium alloy based on AM, AS, EM, EZ, MA, ME, SA, ZA or ZE and that they are after extrusion an elongation at break of at least 17.5%, a compressive strength of at least 300 MPa and impact work measured on notched specimens of at least 45 J. 7. A method of manufacturing a high ductility magnesium alloy and the like. a. by Extrusion, characterized in that the alloy during extrusion  is dynamically recrystallized to have additions or traces of Cd less than 1.8 % By weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain a magnesium alloy based on AZ with at least one addition of Ca, Sr, Li, SE and / or Zr each is at least 0.1% by weight and that they are one after extrusion Elongation at break of at least 17.5%, a compressive strength of at least 350 MPa and impact work measured on unslotted samples of at least 50 J has. 8. A method of manufacturing a high ductility magnesium alloy and the like. a. by Extrusion, characterized in that the alloy during extrusion is dynamically recrystallized to have additions or traces of Cd less than 1.8 % By weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain a magnesium alloy based on MN with at least 1% by weight of Mn and with the addition of Ca, Sr, Li, SE or / and Zr of at least 0.1 wt .-% and that they are one after extrusion Elongation at break of at least 15%, a compressive strength of at least 300 MPa, and impact work measured on unslotted samples of at least 20 J has. 9. A method of manufacturing a high ductility magnesium alloy and the like. a. by Extrusion, characterized in that the alloy during extrusion is dynamically recrystallized to have additions or traces of Cd less than 1.8 % By weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain a magnesium alloy based on MZ or ZM, which is an addition of in particular Ca, Sr, Li, SE and / or Zr each can contain at least 0.1 wt .-%, and that after Extrusion has an elongation at break of at least 15%, a compressive strength of at least 300 MPa and impact work measured on unslotted samples of has at least 40 J. 10. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that according to the Extrusion has a tensile strength of at least 200 MPa.   11. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that according to the Extrusion has a compressive strength of at least 300 MPa. 12. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that according to the Extrusion determines a plastic part of the tension in the tensile test according to the stress-strain diagram from the difference between tensile stress and has yield stress of at least 40 MPa. 13. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the extruded Shaped bodies, in particular bolts, at temperatures in the range from 330 to 380 ° C. be homogenized over 2 to 24 h. 14. A method for producing a magnesium alloy according to at least one of the The preceding claims, characterized in that they have a degree of deformation is extruded from at least 2. 15. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that they with a Extrusion speed in the range of 0.5 to 20 m / min is extruded, preferably at 1 to 18 m / min. particularly preferably at 3 to 16 m / min. all particularly preferably at 5 to 15 m / min. 16. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that according to the Extrusion at temperatures in the range of 80 to 250 ° C, preferably at 100 to 150 ° C, heat treated or outsourced. 17. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that they then a is formed again or is subsequently shaped.   18. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the semi-finished product or the component made from or with the semi-finished product, e.g. B. by Bending, pressing, pressure rolling, stretch drawing, deep drawing, Internal high pressure forming or roll profiling further deformed, processed, joined or / and is surface treated. 19. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the semifinished product or component or component made therefrom by at least one low-heat component Joining processes such as B. gluing, riveting, inserting, pressing, pressing, clinching, Folding, shrinking or screwing and / or at least one heat-generating joining process such. B. composite casting, composite forging, Composite extrusion, composite rolling, soldering or welding, in particular Beam welding or fusion welding, with a similar or different semi-finished product or component is connected. 20. Semi-finished product made of a magnesium alloy or made therefrom Component or composite with such a semi-finished product or component, thereby characterized in that it is according to at least one of the preceding claims was produced. 21. Use of a magnesium alloy manufactured according to at least one of the Claims 1 to 19 as a frame element, element of the vehicle cell or Vehicle outer skin, vehicle cell or vehicle outer skin, cockpit support, Cockpit skin, housing, floor element, floor, cover, tank element, fuel filler flap, Bracket, support, bracket, angle, hollow profile, tube, deformation element, Crash element, crash absorber, impact damper, impact shield, impact carrier, small part, as welded profile construction, for the vehicle body, for seat, window or / and door frame, as a semi-finished product, component or composite on or in the automobile or plane. 22. Use of a semi-finished product made of a magnesium alloy, one of them or thus produced component and / or a composite with at least one  such semi-finished product and / or component as a frame element, element of Vehicle cell or vehicle outer skin, as a vehicle cell or Vehicle outer skin, cockpit support, cockpit skin, housing, floor element, floor, Lid, tank element, tank flap, bracket, support, bracket, angle, hollow profile, Pipe, deformation element, crash element, crash absorber, impact absorber, Impact plate, impact beam, small part, as a welded profile construction, for Vehicle body, for seat, window and / or door frames, as a semi-finished product, component or compound on or in the automobile or airplane.